Surgical implants are well known, and such implants have been heretofore used as spinal fixation devices in correcting deviations of the spinal column, including scoliosis.
Prior known devices for surgical implants have included the use of a pair of spinal rods for aligning a spinal column (see, for example, U.S. Pat. No. 4,369,769), and have also included rods having hooks or the like thereon engagable with vertebrae of the spinal column to achieve spinal alignment (see, for example, U.S. Pat. Nos. 4,361,141; 4,382,438; 4,404,967; 4,369,770; and 4,085,744). In addition, hook devices with locking means for securing hooking devices to a rod have heretofore been suggested in conjunction with surgical implants (see, for example, U.S. Pat. No. 4,433,676).
Spinal implants have heretofore, however, not been found to be completely satisfactory, at least for some applications, due, for example, to inability of the implant to resist rotation, inability of the implant to sufficiently stabilize the spinal column, and/or inability of the implant to maintain the structural integrity of the implant over a period of time.
It is also been heretofore suggested that screws could be utilized in connection with spinal implants (see, for example, U.S. Pat. No. 4,041,939), and a sacral anchor has been heretofore suggested for a surgical implant for use in correction of scoliosis (see, for example, U.S. Pat. No. 4,047,523).
There still remains, however, a need for an improved surgical implant, including a firmly anchored implant for satisfactory aligning and stabilizing the spinal column, and particularly the lumbosacral junction.